Not sure what that has to do with the import of this study but it is an interesting factoid.
Given the great variety of factors contributing to depression, I'm not sure that there are any studies which would attempt to isolate smoking cessation's contribution to a supposed resulting increas in depression.
In any case, Cognitive Behavior Therapy has been demonstrated to be quite effective with most depressions. Of course, that presumes that the individuals concerned are willing and open to changing the way they think.
I think the smoking threads hereon would indicate that the population of smokers is chronically addicted to the way they think; stubbornly, narrowly, rigidly immune to any evidence suggesting that the way they think about smoking is dysfunctional and not factually based . . . etc. etc. etc.
I think their attitude comes from a feeling of harrassment; most of them are tired of being picked on.